Miraculously, Grace was still able to speak and eat but was so self-conscious that she stopped going to school.

After local hospitals failed to help, charity hospital Mercy Ships admitted Grace to perform the four-hour surgery to remove the teenager's tumour, lower jaw and teeth.

Grace had been suffering from the tumour in her lower jaw for ten years as it gradually increased in size.

Deadly: The huge tumour could have suffocated Grace (Image: Barcroft)

Together with her mother she went to the local hospital to get help - but doctors remained baffled by her condition and offered no treatment.

Grace said: "It started from a little swelling inside and the gums started growing little by little.

"We went to hospital and they didn't know what it was - they did nothing."

Grace's mother Christine was left to watch her daughter suffer and had no idea who to turn to for help.

Christine said: "I didn't know what to do - in hospital they just talked a lot but did nothing."

Grace said: "I was sick, I was always indoors, I was not happy anymore, I worried all the time."

Eventually Grace was discovered by a Christian pastor who campaigned to get her medical help.

The pastor posted Grace's story on the church website and a reader told them about Mercy Ships.

Mercy Ships operates the world's largest hospital ship, the Africa Mercy, a converted Danish rail ferry, providing free healthcare services to some of the neediest people in the world.

Sixteen hundred volunteers, including doctors, nurses and teachers from the UK and other countries, provide their time for free each year.

Once on the ship, Grace was given a CT scan to allow the surgeons to see the tumour and plan the surgery necessary to remove it.

Surgeon Dr Gary Parker said: "When it grows where it is in the mouth - as it expands it pushes the tongue into the back of the throat and that's when they get into airway crisis where they can't breathe.